1. 10.2 The Process of Cell Division
December 3-5, 2014

2. Chromosomes
The genetic information(DNA) that is passed from parent to offspring contained in/packaged into chromosomes.
Every cell must copy its genetic information(DNA) before cell division begins.
Each daughter cell gets its own copy of that genetic information.
Cells of every organism have a specific # of chromosomes.
Humans have 23 pairs or 46 chromosomes.

3. Prokaryotic Chromosomes
Prokaryotic cells lack nuclei.
DNA molecules are found in the cytoplasm.
Most prokaryotes contain a single, circular DNA molecule, or chromosome, that contains most of the cell’s genetic information.

4. Eukaryotic Chromosomes
In eukaryotic cells, chromosomes are located in the nucleus, and are made up of chromatin.

5. Chromatin =
--composed of _________ and specific proteins, called _________ proteins.
DNA =
Nucleic acid, one of the 4 macromolecules of life (Ch 2)
Made up of NOCPH: Nitrogen, Oxygen, Carbon, Phosphorus, Hydrogen

6. Nucleosomes
DNA coils around histone proteins to form nucleosomes.

7. Coils and Supercoils
The nucleosomes interact with one another to form coils and supercoils that make up chromosomes.

8. Chromosomes Why it efficient for DNA to be packaged in chromosomes?
What is the role of chromosomes in cell division?
Chromosomes make it possible to separate DNA precisely during cell division.
Why it efficient for DNA to be packaged in chromosomes?
This ensures correct replication and distribution of DNA to the 2 daughter cells during division

9. The Cell Cycle What are the main events of the cell cycle?
During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells.

10. The Prokaryotic Cell Cycle
The prokaryotic cell cycle is a regular pattern of :
Prokaryotes begin to replicate, or copy, their DNA once they have grown to a certain size.
When DNA replication is complete, cells divide through a process known as binary fission.

11. The Prokaryotic Cell Cycle
Binary fission = a form of asexual reproduction during which two genetically identical cells are produced.
Ex: bacteria reproduce by binary fission.
1) chromosome replicates
2) the 2 DNA molecules attach to separate regions of cell membrane
3) network of fibers forms between them
4) fibers constrict and pinch inward to form two separate cells.

12. The Eukaryotic Cell Cycle
More complex…why?
The eukaryotic cell cycle consists of 2 main phases:
Interphase (G1, S and G2 phases)
Mitosis + Cytokinesis (M phase)
Interphase is a period of growth and time between cell divisions.
The M phase is the period of cell division.

13. Concept Map: The Cell Cycle
includes
Interphase
M Phase
(mitosis)
is divided into
is divided into
G1 phase
S phase
G2 phase
prophase
metaphase
anaphase
telophase

14. Interphase: G1 Phase: Cell Growth

15. Interphase: S Phase (Synthesis): DNA Replication

16. Interphase: G2 Phase: Preparing for Cell Division

17. M Phase: Cell Division
In eukaryotes, cell division occurs in two stages:
1) ___________________ is the division of the cell nucleus (4 phases)
2) ______________________ is the division of the cytoplasm.

18. Important Cell Structures Involved in Mitosis
_______________________– each strand of a duplicated chromosome
_______________________ – the area where each pair of chromatids is joined

19. Important Cell Structures Involved in Mitosis
___________________ – tiny structures located in the cytoplasm of animal cells that help organize the spindle
___________________ – a fanlike microtubule structure that helps separate the chromatids

20. Mitosis 1st phase: Prophase
Duplicated chromosome ___________________ and becomes visible.
The________________move to opposite sides of nucleus and help organize the spindle.
The spindle forms and DNA strands attach at _____________________
________________disappears and ________________________ breaks down.

21. Mitosis: 2nd Phase Metaphase
____________________ line up across the center of the cell.
The ______________________ connect the centromere of each chromosome to the two poles of the spindle.

22. Mitosis: 3rd phase Anaphase
Centromeres pulled apart and the chromatids separate to become individual chromosomes.
The chromosomes separate into two groups near the poles of the spindle.

23. Mitosis: 4th Phase: Telophase
The chromosomes spread out into a tangle of chromatin.
A______________________ re-forms around each cluster of chromosomes.
The spindle breaks apart, and a nucleolus becomes visible in each daughter nucleus.

24. Mitosis What events occur during each of the four phases of mitosis?
During prophase, the genetic material inside the nucleus condenses and the duplicated chromosomes become visible. Outside the nucleus, a spindle starts to form.
During metaphase, the centromeres of the duplicated chromosomes line up across the center of the cell. Spindle fibers connect the centromere of each chromosome to the two poles of the spindle.
During anaphase, the chromosomes separate and move along spindle fibers to opposite ends of the cell.
During telophase, the chromosomes, which were distinct and condensed, begin to spread out into a tangle of chromatin.

25. Cytokinesis Cytokinesis is the division of the cytoplasm.
Cytokinesis completes the process of cell division – it splits one cell into two.
The process of cytokinesis is different in animal and plant cells.

26. Cytokinesis in Plant Cells
Cytokinesis in Animal Cells
The cell membrane is drawn in until the cytoplasm is pinched into two equal parts.
Each part contains its own nucleus and organelles.
Cytokinesis in Plant Cells
The cell membrane is not flexible enough to draw inward because of the rigid cell wall.
Instead, a cell plate forms between the divided nuclei that develops into cell membranes.
A cell wall then forms in between the two new membranes.

27. The Stages of the Cell Cycle

28. ALL Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm